Nowadays, with the development of communication technology and continuous expansion of requirements of user experience, a bigger screen and a thinner shape are becoming the mainstream trend in the development of appearance of mobile phones. Due to requirements on a high bandwidth, the existing mobile phone generally uses a basic antenna form of monopole antenna. However, as the realization of this form requires considerable headroom, a projection area of the screen becomes a restricted zone of the antenna design. In other words, the growing of the screen and the shrinking of the keyboard area make the design space of the antenna in the horizontal plane become continuously shrunk. Due to the pursuit of a thinner shape, the longitude design space is also restricted. How to design an antenna satisfying performance requirements by making use of the space has become a practical problem which must be faced up by the antenna design.